<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
    .wrap {
        overflow: hidden;
        width: 200px;
    }
    .container {
        transition: all .5s;
        display: flex;
        flex-direction: column;
        height: 100vh;
        margin: 0;
        padding: 0;
    }
    .item {
        /* flex-shrink: 0; */
        width: 100px;
        position: relative;
        /* background: orange; */
        box-sizing: border-box;
        border: 1px solid orangered;
    }
    .item-other {
        flex: 1;
    }
    </style>
</head>
<body>
    <div class="wrap">
        <ul class="container">
            <li class="item" style="background:orchid">333</li>
            <li class="item" style="background:gray">333</li>
            <li class="item-other" style="background:orange">333</li>
        </ul>
    </div>
</body>
</html>